I was inspired by Lock's blog post, Social Cues I Just Keep Missing, to write this response. My intended response seemed too long for a comment.
Lock discusses how those of us who are asexual, and especially if we are neuro-atypical or have mental illnesses or disorders, can have some difficulty interpreting sexual social cues or can be surprised at finding that we give off cues by accident. Lock also writes about how there are those who take advantage of cues, though they may be unaware of the miscommunication in some cases.
It reminded me of how, during my freshman year of college, I found myself in a situation that I'd been completely unaware of stepping into. Late one evening a male acquaintance invited me to his dorm to hang out with him and his girlfriend and have some drinks. They were both already drunk, and his girlfriend was on the verge of passing out. We conversed for a while, and I don't remember too much of the evening. I do remember that just as I was leaving he said (with disappointment and frustration), "I invited you over because I thought you were going to have sex with me and my girlfriend. Why did you come over?" To this day I am totally baffled at the possibility I gave off some cue or failed to pick up on his cues. I have no idea how this happened.
It's also possible though that there were no cues, and his statement was a last desperate attempt to guilt me into having sex with him and his (by then unconscious) girlfriend. As a side note, this person also claimed to be a feminist, which is horrifying in a very special way.
I think that people who rely on sexual cues and nonverbal communication are treading dangerous waters, particularly when approaching new potential sex partners. If they're trying to get someone to have sex without asking for consent, they risk sexually assaulting someone.
Also, the tendency to ignore rejection I think not only has to do with wanting sex desperately, as Lock suggests, but also with masculine imperialism or something of that nature. I'm not suggesting that people go around thinking, "I'm going to ignore this rejection because I want to bolster my confidence and sense of power by conquering this person sexually," but I think that kind of attitude is subliminal culturally.
The more I think about social cues, and how confusing they are and how they vary geographically and culturally, the more I am convinced that they actually hinder intimacy rather than promote it when we rely on them. The cues that we each learn vary so widely that it's unlikely that any two people will use and understand the same set of nonverbal cues. While the cues themselves do not hinder intimacy or cause sexual assault, the cultural attitude that there is a universal code which we can learn and interpret rather than communicate verbally is a serious problem. We can't help it that we send nonverbal signals. But it is problematic that we sell books and magazines and have television programs that claim to instruct on social cues so one can get intimate without asking, taking short cuts to avoid being uncomfortable.
If you have to seriously question whether someone's facial expression or way of looking at you is sending a message about wanting to perform a particular act, it's probably time to start asking questions. And if you can't ask questions because you won't accept rejection, then you shouldn't try to engage at all. If all you have to go on when you advance sexually is social cues which you've interpreted in your own favor, and you haven't asked for consent, then you could be sexually assaulting that person. It doesn't matter if you feel like your intentions are harmless when you touch someone without asking first, not asking is a way of dominating even if all you are doing is giving a hug.
I'm not suggesting that you should ignore nonverbal cues if you think that someone is hinting something to you strongly, whether it is "come closer," or "get away," but that you should also check in and verbally confirm your suspicions. While those of us who have more difficulty than others noticing social cues may have heightened awareness of how confusing they are, I think that this confusion only confirms the necessity to not rely solely on nonverbal communication, because social cues are different for everyone.